The Present Disclosure relates, generally, to a connector for a multilayered board used to connect a flat cable, such as a flexible printed cable, to a middle layer of a multilayered board.
Multilayered boards, which are printed circuit boards formed in layers, are commonly used in electronic devices, such as mobile phones and smartphones, in response to the increasing density of wiring patterns. A flat cable, such as a flexible printed cable, is used to connect a multilayered board to an electronic component module and to connect multilayered boards to each other.
When a flat cable is connected to a multilayered board, a connector is installed in the surface layer of the multilayered board, and the flat cable is connected to the connector. When a connector is installed in the surface layer of a multilayered board, the connector increases the thickness dimension of the multilayered board, and the connector occupies a large amount of area on the multilayered board. These connectors may impede further miniaturization of multilayered boards and electronic devices.
Connecting a flat cable to a middle layer of a multilayered board has recently been proposed. For example, a multilayered board connecting mechanism has been proposed in U.S. Pat. No. 7,238,044, in which a flat cable is connected electrically to a multilayered board by inserting the flat cable into an insertion slot formed on the board-thickness surface of the multilayered board. The content of the aforementioned Patent is hereby incorporated herein in its entirety.
FIG. 15 is a simplified cross-sectional view showing a conventional connector for a multilayered board. As shown, the connector used to connect the flat cable 3 to a middle layer of the multilayered board 2 has a board-side connecting portion 801 arranged inside an insertion slot 2a formed on a board-thickness surface of the multilayered board 2, and a cable-side connecting portion 901 provided on the tip of the flat cable 3. A plate-spring terminal 851 provided on the board-side connecting portion 801 makes resilient contact with the terminal portion of the cable-side connecting portion 901 in response to the insertion of the cable-side connecting portion 901 into the insertion slot 2a. Alternatively, as disclosed in the '044 Patent, the flat cable 3 is connected electrically to a middle layer of the multilayered board 2 by a plate-spring terminal provided on the cable-side connecting portion making resilient contact with a terminal of the board-side connecting portion.
However, a connector for a multilayered board of the prior art, as shown in FIG. 15 and described in the '044 Patent, sustains the reaction force of the plate-sprint terminal 851 in the top laminated substrate (first laminated substrate 2b) or the bottom laminated substrate (third laminated substrate 2d) of the insertion slot 2a. As a result, the contact space of the plate-sprint terminal 851 (the amount of displacement by the spring) is affected by variations in the dimensional precision and strength of multilayered boards 2, and/or resistance to the resilient force of the plate-spring terminal 851 deforms the multilayered board 2. Therefore, contact stability may not be achieved.